The United Nations' top official on refugees has slammed Australia before an international audience, saying he is "dismayed" by the country's treatment of asylum seekers in detention in the context of the accelerating migration crisis in south-east Asia and Europe.

The UN High Commissioner for Human Rights, Zeid Raâ€™ad Al Hussein, told the Human Rights Council overnight in Geneva that he was "alarmed" by the current migration crises, calling on countries to put human rights first and to approach the issue "far more" comprehensively.

"The paramount concern of all actors must be the human rights of the people who have embarked on their desperate voyage out of fear and need," he said.

This year more than 1050 people have died at sea after fleeing from Myanmar and Bangladesh, while more than 1800 have died in the Mediterranean, Mr Hussein said.

"I am also dismayed that in Australia, people on boats intercepted at sea are sent to detention centres where conditions are inadequate," he said.

"In the first quarter of this year, 25,000 people have set out to sea from Myanmar and Bangladesh – some fleeing persecution in Myanmar, and others fleeing the poverty that besets both countries."

He said a "large proportion" of them were stateless and refugees in need of international protection and that people smugglers had violently abused and robbed many people who were attempting to leave their countries.

"As the special rapporteur on human rights in Myanmar told the council in March, Rohingya people in [displacement] camps have told her that they had only two options: 'stay and die' or 'leave by boat'," he said.

Daniel Webb, director of Legal Advocacy at the Human Rights Law Centre, said an urgent humanitarian crisis was unfolding and Australia should do more to help.

"A wealthy, developed and fundamentally decent nation like Australia should be part of the solution. Instead, we're being called out on the world stage as part of the problem," he said.

"While the UN is urging countries to respect international law and share responsibility, Australia is breaching international law in order to shift it."

This is not the first time Mr Hussein, who is a Jordanian prince, has criticised Australia for its treatment of asylum seekers.

In his maiden speech as Commissioner for the UNHCR in September, he said Australia's policy of offshore processing of asylum seekers and intercepting and turning back vessels was leading to a "chain of human rights violations, including arbitrary detention and possible torture following return to home countries".

Last week when asked whether Australia would offer resettlement to any of the thousands of migrants caught up in south-east Asia's refugee crisis, Prime Minister Tony Abbott replied "nope, nope, nope".

In March, after a UN report found that Australia was violating the rights of asylum seekers on multiple fronts, Mr Abbott said he was "sick of being lectured to by the United Nations".

"I really think Australians are sick of being lectured to by the United Nations, particularly, particularly given that we have stopped the boats, and by stopping the boats, we have ended the deaths at sea," Mr Abbott said.

"The most humanitarian, the most decent, the most compassionate thing you can do is stop these boats because hundreds, we think about 1200 in fact, drowned at sea during the flourishing of the people-smuggling trade under the former government," he said.